Fuse for projectiles



Jan. 15, 1946. J SEMPILE 2,392,884

FUSE FOR PROJECTILES Filed Jan 27, 1941 2 Sheets-Sheet 1 1 4 I s 1 INVENTOR M40 6. MW

FUSE FOR PROJECT ILES Jan. 15, 1946.

Filed Jan. 27, 1941 2 Sheets-Sheet 2' Zc 6c g. .Xl'

INVENTOR VII.HT'X' ,4", {1' gm 'W MEL/am Patented Jan. 15, 1946 UNITED STATES RAT E'NT *TOF F'I-C E FUSE FOR PROJECTILES :John B.:Semple, Sewickley,'-Pa.

Application January 27, 1941,Serial No."376,079

4 Claims.

This invention relatesto fuses for projectiles; and, while ofgeneral applicability, it has been developed in application tofuses .for shells for guns ofsmall calibre,-and particularly anti-aircraft guns. The objects in view are simplicity of structure combined with safety in handling and firing and certainty infunctioning.

In the accompanying'drawings Fig.1 is a view in axial section, and to-enlarged scale, of a fuse in which the invention is embodied. The invention centers in a certain detonator. block movable in its mounting withinthe fuse body from unarmed and safe position to active, armed. position; and, in Fig. I,thls detonator block appears in elevation and in its inactive and safe position. Fig. II is a view corresponding inother respects to Fig. I, in which, however, the detonator block appears partly insection and in its active, armed position. Fig. III is a view in side elevation of the detonator block alone, and in' this view (as also in Fig. I) a certain set-back bolt that the detonator block carries isshown in the extended position that it maintains while securing the detonator block in unarmed and safe position. Figs. IV and V are views ofthe detonator block in transverse section, on the planes indicated severally at IV-'IV -a'nd"VV, Fig. III. Fig. VI is a view corresponding other respects to Fig. HI, but showing'the set-back bolt in the retracted position to'which it comes, leaving the detonator block free within the fuse body to move to armed position. Fig. VII is a view to larger scale and in section showing the detonator block and immediately adjacentportions of'the body. The plane of section is indicated at VII-VII, Fig. III. Fig. VIII is a view in plan of an element that in Fig. VII is shown in section. Fig. IX is a fragmentary view to larger scale of a'portion of' the structure as seen in FigI'I and illustrating a refinement in detail. 'In this figure, however, the detonator block is shown in vertical and axialsection. Fig.2! is a view in elevation of an element that in FigQIX is shown in section. Figs. XI and-XII are views in axial section, and on planes at right anglesto' one another, of" a modifiedfuse-in which" the detonator block of the invention is adapted to and combined with a simplification offiring' mechanism.

Referring first to Figs. I-VIII, a fuse is shown arranged within 'a body- I. The body-i will be recognized to be -the anterior pointed end of a shelLadapted to be screwed to place in assembly with the essentially "cylindrical body of the'shell. Thisanteriorend of the shell becomes indeed the ruse body. it is an integral, one=piece body,as-

sembled with the shell by means of a single screw-thread union. This fuse body I is formed with an axial bore'2, and through the bore, in the functioningof. the fuse, the firing of a primer 3 is transmitted rearwardly to a booster charge 4 that fillsan enlargement of the bore'an'd that (as will be understood) is, in the assembly, in position to transmit detonation to the burster charge that fills the body of the 'shell.

A transverse cylindrical bore 5, whose axis lies in a common plane with that of'the axial bore through the fuse body, is sunk in the side of the integral body I toward the opposite side. "It extends beyond the axial bore through thebody I but does not penetrate'to the opposite side of the body I. It intersects at right angles the axial bore 2. In this transverse bore an essentially cylindrical detonator blo'ck'fi is'carried. Transversely through the detonator block extends adiamet'rical' bore 1, and the parts are so arranged and proportioned that, in the range of turning of the block Within its bore, its diametrically extending bore comes from a'remote position to a position of coincidence with and indeed forms part of the axial 'borethrough' the fuse' body. That is to say, the detonator block'fi'is a makeand-break device that, in alternate positions, either obstructs or establishes" the continuity of the axial bore throughthe'fuse body. The diametrically extending bore 1 through the detonator block is filled with a column of detonationtransmitting material, conveniently assembled within a capsule and then brought to place within thebore. The column within the bore, in this instance, includes the charge "3 of primer composition itself, backed by a ported anvil block-8 (cf. Figs. VII and VIII) and covered by a suitable penetrable protective septumlL-as of metal, and, in succession, to rearward of the primer composition the charge includes a body ll! of lead azid or other initiating explosive, and a body ll of tetryl, the substance of which the booster charge 4 also is composed.

"In the embodiment of the inventionshown in Figs. I-VIII a firing'pin: I2 is arranged in theranterior end of the axial bore throughtthe body I. When the detonator block fi is'in armed'position the body3 of primer composition is in position for the impingement upon itof the firing pin. The firing pin [2 consists of-ashank pointed at the posteriorndandprovided at the anterior end with an enlarged head thatzis arranged within the widenedforward' end of the bore 2, with clearance for free movement. A; protecting septum |3,:a: thinplateofialuminum for example,

closes the bore at the forward end. Sufilcing for ordinary protection and for the exclusion of dirt and moisture, this cover-plate I3 is destructible upon impact of the shell upon a target, so that the force of the impact, communicated to the firing pin, drives the pin rearward within its bore, causing it to penetrate the septum 9 and fire the body 3 of primer composition. The ensuing flash of the charge, passing through the ports in the anvil plate-8, reaches and detonates the body ll! of lead azid or other initiating explosive. Detonation of body imparts detonation to body I l and through body H to the booster charge 4,

with which the body I l is, in this position of the detonator block, functionally continuous.

The unarmed and safe position of the detonator block i that shown in Figs. I andVII;

and, specifically, when in this position'the detonator block 6 is turned through an angle of 60 counter-clockwise from its armed, firing position. So long as the detonator block continues in this unarmed position, the fuse is safe. Premature and accidental firing of the sensitive body ID of lead azid cannot reach booster charge 4 to fire it.

The diametrical bore 1 through the'detonator block 6 is, as shown in Figs, I and II, arranged in a medial portion in the length of the block, leaving the ends of the block 6 to be adapted in particular Ways and to serve particular purposes. In one end of the'block (the left-hand end, as seen in Fig. I)' a diametrical bore is formed, and is so placed that, when the block 6 is in its unarmed position, this ,bore extends in fore-and-aft position, parallel with the axis of the'shell. In this bore a set-back bolt M is arranged, and the set-back bolt is by a shearpinli': normally secured in the protruding position shown in Figs. 1, III, and V. When in its extended position the set-back bolt at its anterior end extends into a slot "5 cut in the rim of bore 5 for its reception, and so secures the detonator block against turning. The bore 5, open to the left for the introduction of the detonator block, isclosed by, a screwed-in block I1, the bore, being. widened, so that the applied block closes the slot also. The inner smooth righthand face of the block I! forms in the assembly an end wall of the cylindrical chamber within which the detonator block 6 is arranged.

The detonator block 6 at its opposite, 'righthand end is cut away. Diametrically opposed recesses l8 are formed that leave between them a diametrically extending vane llf It will be found advantageous to form the recesses 18 as shown in Fig. IV, in the shape of symmetrically placed segments .of cylindrical bores sunk in the head of the cylindrical block 6. Thus in simple manner the mass of the remaining vane l9 is'widely distributed from the axis of the block 6. The vane I9 is so disposed that, when the block is in its unarmed position (Figs. I

and VII,-the vane is in the obliqueposition shown in Figs. I and IV. When the shell is in flight, rotating as it flies, and when the detonator block is free within its bore, centrifugal force.-

acting upon theblock with. this obliquely disposed vane will effect a turning of the block withinits bore until the mass, previously unbalanced, comes to balance with" respect to the impelling force, that is tosay (other things being equal), until the mid-diametrical plane .of

the vane 19 is perpendicular to the axis of shell rotation. In case the block 6 with itsbcre l in alignment with the bore 2 is not in the distribu tion of its mass truly symmetrical with respect to the-fuse axis, the position of the vane 19 will be minutely adjusted empirically, to afford compensation for such asymmetry. But for that, the vane will be so placed that its middiametric plane is perpendicular to the axis of bore a. Centrifugal force then will be effective upon the block 6 to turn it clockwise (Figs. IV and VII) until the vane l9 extends exactly in perpendicular position (Fig. II) and bore 1 is exactly aligned with here 2.

Restating this matter, the mass of the detonator block is, by virtue of the vane l9, asymmetrical with respect to its cylindrical axis; and, when in unarmed position and in rotation on the shell axis (an axis perpendicular to its own axis), it is in a state of unbalance with respect to the centrifugal force due to such rotation. In consequence, it turns upon its own axis until it comes to a position of balancewith respect to such centrifugal force. That position of balanceis the armed position. v

It is to be observed thatby the provision of the vane 19 extending from the block 6, such small asymmetry as may be due to difference in mass between the body of the block and of the charge that fills the bore within it iscloaked and rendered ineffective: the asymmetry af forded by the vane will be quantitatively'greater and prevailing in effect. 7 V v It'is advantageous that a slight indentation or recess 20 be formedin the cylindrical surface of the detonatqr block 6, so placed that, when block 5 is assembled in the unarmed position acceleration: that is to say; until after theshell' leaves the gun": And, although the shell is. set in rotation, this engagementofthe firing pin in recess 2!), is effective, to secure'detonator block 6 in its unarmed position. That is to say, the fuse is bore-safe. When,.however,,,the shell has left the gun and the acceleration 6f the firing charge is spent, centrifugal force exertedupon the unbalanced detonatorvblock 6 is'eff'e'ctive to turn the block within its bore,'forcing. forward 'the'firing pin [2. that now offers no effective resistance. This turning underlcentrifu'gal force carries the block iifrom unarmed (Fig. n to armed position (Fig; II and maintains it durin g flight in armed-position. On impactf-the firing pin-is drivenrearward, penetrating the body of primer compositin. The .fuse functions, and the shellis detonated;

So long, however, as the bolt l4 continues, locked by the shear-pinin its extended position,

the shell cannot-be detonated, even though the initiating elements of the fusemight prematurely It will be remarkedof the fuse thus shown and described that it is a structure of notable simplicity and strength; the parts are of such shape as to permit of die-casting very little machining has .to be done upon them; and only -two screwthreads have to be out; The detonator b c s integral; it is of simplest contour, essentially cylindrical. by a charge-carrying bore; at one end it is recessed to receive the set-back bolt; and at the other end the cylindrical contour is cut away, to afford functional unbalance. Assembly is very simply effected. The detonator block 6, equipped with its pin-held set-back bolt I4, is loaded with its charge (which, previously prepared, and contained in a capsule, may be slipped to place), and is applied as a unit to the unitary fuse body I (in which the booster charge 4 has already been placed). In making application, the protruding end of the set back bolt l4, engaging the slot l6, brings the detonator block precisely to position (to the unarmed, safe position). The closure I! is then applied. The firing pin is introduced through the nose of body I, and the closure I3 is applied. The component parts are easily produced, and easily assembled, and all is inexpensive. All this with precisionand certainty in functioning, so that the fuse is at once simple in unexcelled degree, safe in unexcelled degree, and sure in unexcelled degree.

Fig. IX illustrates a modification in which, beneath the block Ila that closes the bore 5, a plate 2| is introduced. It may be a thin plate of aluminum. This plate may be placed in a rebated seat in the body I. It has a lip 22 outstanding from its otherwise circular margin, of such size and shape as to fill the groove I 6, to the exclusion of dirt. Such a plate being provided, secured in place beneath block Ha, it is not necessary that the block Ila be enlarged, itself to cover and enclose the groove 16.

In the modification shown in Figs. XI and XII there is no firing pin. The primer composition 30 suitably protected in a light metal carrier is arranged in the forward end of the axial bore 20, and rests to rearward upon an anvil 8c rigidly mounted in the body He. The primer charge under stress of impact will be fired upon the anvil. The anvil is ported, and the flash of firing is delivered rearward through bore 20. The charge in the detonator block 6c in this case consists of the body Ific of lead azid upon which (suitably protected, as by shellac) the flash from the primary charge makes immediate impingement. To the rear of the body of lead azid is the body He of tetryl. With the modifications indicated, the structure functions in the manner described.

In all of the figures the block is shown to be of such length as substantially to fill the bore from end to end. In Fig. XI the block is shown to be round-ended; and, in consequence, it turns the more freely in the bore. The transverse bore 50 for the detonator block 6c extends completely through the block lo and is closed at the ends by an encircling band He.

The structure of the invention in all of its In its medial portion it is penetrated forms includesinded, is characterized by-a detonator block that is arranged in a transverse bore in the fuse body and that turns under centrifugal force from unarmed to armed position; a detonator block that in its turn is provided with a transverse bore. The transverse bore in the detonator block carries a charge, and this charge in the turning of the detonator block, is brought from a position of safety to an armed position, in which it is aligned with and forms part of a line of ignition and detonation from firing means at the nose to a booster charge at the base of the fuse body. The turning of the fuse body upon its transversely disposed axis is effected by centrifugal force incident to shell rotation effective upon a detonator block whose mass is with respect to that force unbalanced. V

I claim as my invention:

1. A fuse for a projectile including a body having a transverse open end bore and an intersecting longitudinal bore, the transverse bore having an outwardly opening groove in its rim, a cylindrical detonator block insertable laterally in said bore for rotatable mounting therein and responsive to centrifugal force to arm the fuse, said block being provided with a bore extending diametrically therethrough for reception of a primer and adapted to register with the longitudinal bore when the fuse is in armed condition, said block being further provided with a recess, a setback bolt in said recess and provided with a protuberance extending into said groove to hold the block in unarmed position and to guide the block in inserting it in the transverse bore, a pin normally holding the bolt above the bottom of the recess, said pin being arranged to be sheared upon setback to allow the withdrawal of the protuberance from said groove to partly arm the fuse, the structural relationship between the block and fuse 0 body being such that the block and parts carried thereby are insertable laterally in said body as a unit, and means for closing the open ends of the transverse bore and groove.

2. The invention of claim 1 characterized in that the transverse bore in the fuse body is of greater diameter at its open end than the diameter of the block and sufliciently so to include the depth of said transverse groove, and unitary means for closing the outer end of said transverse bore including said groove.

3. The invention of claim 1 characterized in that the means for closing the transverse bore comprises a block threaded into the open end of the bore.

4. The invention of claim 1 characterized in that there is a diametrically disposed vane at the inner end of the rotatable block, said vane increasing in cross-sectional area from the axis of said block to its periphery to increase the mass of the block adjacent its periphery.

JOHN B. SEMIPLE. 

